The currently available pneumococcal vaccines are effective in preventing invasive pneumococcal disease (IPD), according to a study in the Medical Journal of Australia.
However, it is likely that, with combined direct and indirect effects, newer conjugate vaccines could prevent even more IPD than could be prevented with the two current vaccines.
AdvertisementDr Jeffrey Hanna, a public health physician at the Cairns Public Health Unit of Queensland Health, and colleagues compared trends in IPD in non-Indigenous people in north Queensland before and after the introduction of two funded pneumococcal vaccines in 2005, and examined the proportion of cases that occurred after the vaccine roll-out that could have been vaccine-preventable.
One of the vaccines (7vPCV), protecting against seven pneumococcal serotypes, was made freely available to children; the other (23vPPV) includes the same seven serotypes plus an additional 16, and was made freely available to adults aged 65 years or older.
Dr Hanna said that, after the introduction of the vaccines, there were significant declines for all age groups in the average annual incidence of IPD and a powerful indirect effect of the 7vPCV in preventing IPD in adults of all ages.
In children aged under five, there was a 91 per cent decline in the incidence of IPD caused by the seven serotypes included in 7vPCV; in adults, there was a 62 per cent decline in IPD due to the same seven serotypes for those aged 15-64, and a 77 per cent decline for those aged 65 and over.
"The marked decline (34 per cent) in overall IPD incidence in 2006-2009 can be attributed to pneumococcal vaccination," Dr Hanna said.
"Particularly impressive was the 77 per cent decline across all ages of IPD caused by 7vPCV serotypes.
However, the study also found that IPD serotype 19A, which is not included in 7vPCV, has emerged as a dominant serotype in the region.
"Continued surveillance will be essential to monitor further trends in IPD in north Queensland and elsewhere."
The Medical Journal of Australia is a publication of the Australian Medical Association.